/**
  * checks for an existing hint relating to current question and redirects
  * with corresponding failure message on failure
  *
  * @access	private
  * @param	integer	$hintId 
  */
 private function checkForExistingHintRelatingToCurrentQuestionAndRedirectOnFailure($hintId)
 {
     $questionHintList = ilAssQuestionHintList::getListByQuestionId($this->questionOBJ->getId());
     if (!$questionHintList->hintExists($hintId)) {
         ilUtil::sendFailure($lng->txt('tst_question_hints_invalid_hint_id'), true);
         $ilCtrl->redirect($this, self::CMD_SHOW_LIST);
     }
 }